In general, so-called RF tags including IC chips, in which predetermined information on articles and objects is readably and writably stored, are broadly used to the various articles and objects.
The RF tag is also called an RFID (Radio Frequency Identification) tag, an IC tag, a non-contact tag or the like. The RF tag is a microminiature communication terminal, which is obtained by shaping, in the form of a tag (baggage tag), a so-called inlay (inlet) where an electronic circuit including an IC chip and a radio antenna is sealed or coated with a substrate such as a resin film. In the RF tag, reading-only the predetermined information from the IC chip, writing-once it in the IC chip, and reading it therefrom and writing it therein are possible by a reader/writer via radio.
Furthermore, when the predetermined information is written in such an RF tag and the thus treated RF tag is then attached to, e.g., each of various articles and objects, the information recorded in the RF tag is picked up by the reader/writer, to enable recognition, output, display, update and the like of the information recorded in the tag as the predetermined information on the articles.
In such an RF tag, several hundred bits to several kilobits of data can be recorded in a memory of the IC chip, and a sufficient amount of the information can be recorded as the information on each of the articles and the like. Furthermore, communication can be performed with a reading/writing device side in a non-contact manner, and hence there is no fear of wear, damage, dirt or the like on a contact. Additionally, the tag itself can include no power source, and hence processing, miniaturization and thinning of the tag can be performed in compliance with each object.
Furthermore, by use of such an RF tag, it is possible to record various pieces of information on each article to which the tag is attached, e.g., a name, an identification symbol, a content, components, a manager, a user, a use state, a use situation and a date of the article. Therefore, a large variety of pieces of information, which are impossible by characters, a bar code or the like printed and displayed on the surface of a label, can correctly be read and written simply by attaching the miniaturized and thinned tag to the article.
However, when this RF tag is attached to, e.g., each of articles and objects made of a metal, the RF tag is disadvantageously influenced by a conductivity of the metal, which causes difficulty in radio communication.
That is, when the RF tag is attached to each article, a magnetic flux is generated by the RF tag in such a direction as to pass through the article. Therefore, when the tag is attached to the article made of the metal, magnetic waves or electromagnetic waves emitted by an antenna section are absorbed on a metal side to disadvantageously generate a heat loss or the like, thereby causing a situation where communication characteristics of the tag are impaired. Therefore, when the usual RF tag for general use is attached to each of the articles and objects made of the metal as it is, the tag may incorrectly operate or the radio communication with the reader/writer may not be able to be performed.
Patent Documents 1 and 2 suggested that when the RF tag is attached to each metal article, a constitution of the RF tag is changed to a constitution for exclusive use in the metal to avoid the influence from the metal.
Specifically, in the heretofore suggested RF tag for the metal, reflecting means or a dielectric substance formed in a sheet state or the like is disposed in the tag on a side facing the metal which becomes an attaching object. Furthermore, the magnetic flux emitted by the tag is reflected by this reflecting means or dielectric substance, or passes through the dielectric substance, thereby preventing the generation of the heat loss or the like from being caused by absorbing the magnetic waves or electromagnetic waves on the metal side.
Furthermore, in addition to the abovementioned influence from each of the metal articles, the RF tag in a state of the inlay where the IC chip and the antenna are simply coated with the film easily receives an influence by an impact, water, temperature change or the like, and there is the disadvantage that a failure, wrong operation, breakdown or the like easily occurs.
Therefore, Patent Document 3 suggested that the RF tag in the state of the inlay is received and sealed in, e.g., a case made of a resin, to improve a weather resistance, a heat resistance, and a water repellence.
Furthermore, Patent Documents 4 and 5 taught that RF tags may be attached to metal pipes constituting trucks made of a metal or the like, e.g., a cage truck and a cart rack shown in FIG. 9A and FIG. 9B.
When “an IC tag device” for a metal as suggested in Patent Document 4 is attached to the metal pipe constituting the truck made of the metal, an inlet of an RF tag is sandwiched between a packing section to be fixed to the metal pipe and a protective layer disposed on an outer side of the packing section, to avoid an influence from the metal pipe.
Furthermore, in “a radio IC tag holder” disclosed in Patent Document 5, when a radio IC tag (an RF tag) is attached to the metal pipe, the radio IC tag is received in the holder which is to be wound around and attached to an outer periphery of the metal pipe and which comprises an electromagnetic wave cutoff layer, whereby the influence from the metal pipe is avoided.